Method of controlling weeds with phenoxyethyl carbamates

ABSTRACT

The compounds of the class halo-substituted phenyl oxyethyl esters of N-alkyl carbamic acids having the general formula   WHEREIN R and R1 are selected from the group consisting of hydrogen, lower alkyl having from one to six carbon atoms, inclusive, and lower alkenyl having from two to six carbon atoms, inclusive, at least one of R and R1 is a group other than hydrogen; and R2 is selected from the group consisting of nuclearly substituted phenyl, wherein said substituents are from one to five halogens, inclusive, especially chlorine; for example, 2,4-dichlorophenoxyethyl-N-methyl carbamate and 2,4,5trichlorophenoxyethyl-N,N-di-n-propyl carbamate. The compounds of the class are useful as preemergence and postemergence herbicides. The compounds can be prepared by condensing a halophenyl oxyethanol and an alkyl isocyanate or condensing a halophenyl oxyethanol with an N,N-dialkyl carbamyl chloride.

United States Patent Francher 51 Mar. 28, 1972 [72] Inventor: Llewellyn W. Francher, 22 Valley View Drive, Orinda, Calif. 94563 [22] Filed: Oct. 27, 1969 [21] Appl.No.: 869,961

Related US. Application Data [60] Continuation of Ser. No. 798,233, Sept. 19, 1968, abandoned, which is a division of Ser. No. 604,136, Dec. 13, 1966, Pat. No. 3,439,021, which is a continuation-in-part of Ser. No. 367,879, May 15, 1964, abandoned.

[52] U.S.Cl ..71/106 [51] lnLCl. ..A01n 9/24 [58] FleldofSearch ..71/106,122

[56] References Cited UNITED STATES PATENTS- 2,573,769 11/1951 Lambrech ..71/122 2,712,990 7/1955 Swezey ..71/106 2,765,224 10/1956 Lambrech .71/106 2,823,224 2/1958 Senkbeil et a1. .71/106 2,823,225 2/1958 Senkbeilet al. .71/106 2,933,383 4/1960 Lambrech .71/106 3,074,998 1/1963 Whetstone et al. .71/106 3,330,642 7/1967 Barron et a1 ..71/106 3,439,021 4/1969 Fancher ..71/106 FOREIGN PATENTS OR APPLICATIONS 728,995 4/1955 Great Britain ..71/106 Primary Examiner-Lewis Gotts Assistant Examiner-G. Hollrah Attorney-Edwin H. Baker and Wayne C. Jaeschke [5 7] ABSTRACT wherein R and R are selected from the group consisting of hydrogen, lower alkyl having from one to six carbon atoms, inclusive, and lower alkenyl having from two to six carbon atoms, inclusive, at least one of R and R is a group other than hydrogen; and R is selected from the group consisting of nuclearly substituted phenyl, wherein said substituents are from one to five halogens, inclusive, especially chlorine; for example, 2,4-dichlorophenoxyethyl-N-methyl carbamate and 2,4,5-trichlorophenoxyethyl-N,N-di-n-propyl carbamate. The compounds of the class are useful as preemergence and post-emergence herbicides. The compounds can be prepared by condensing a halophenyl oxyethanol and an alkyl isocyanate or condensing a halophenyl oxyethanol with an N,N- dialkyl carbamyl chloride.

METHOD OF CONTROLLING WEEDS WITH PHENOXYETHYL CARBAMATES This is a continuation of application Ser. No. 798,223, filed Sept. 19, 1968, now abandoned, which is a division of application Ser. No. 604,136, filed Dec. 13, 1966, now U.S. Pat. No. 3,439,021, which is a continuation in part of application of Ser. No. 367,879, filed May 15, 1964, now abandoned.

This invention relates to certain new and novel organic compounds which may be used as herbicides. More specifically, this invention relates to certain substituted phenyl oxyethyl-N-alkyl carbamates and to the use of such compounds in herbicidal compositions.

The compounds comprising the instant class are esters of N- alkyl carbamic acids and correspond to the general formula wherein R and R are selected from the group consisting of hydrogen, lower alkyl having from one to six carbon atoms, in-

clusive, and lower alkenyl having from two to six carbon atoms, inclusive, at least one of R and R is a group other than hydrogen; and R is selected from the group consisting of nuclearly substituted phenyl, wherein said substituents are from one to five halogens, inclusive, especially chlorine.

As examples of organic lower alkyl groups having from one to six carbon atoms which can be used for R and R are methyl, ethyl, propyl, butyl, and hexyl. Similarly, examples of lower alkenyl having from two to six carbon atoms are vinyl, allyl, iso-propenyl, Z-butenyl, 2-pentenyl, 1,3-butydienyl, and 2-hexenyl.

The compounds herein contemplated can be prepared by several methods. The monoalkyl carbamic acid derivatives were prepared by known methods, such as the reaction between the corresponding halo phenyl oxyethanol and an alkyl isocyanate. The addition of an organic base, such as triethylamine and the like, acts as catalyst to facilitate the completion of the reaction. The reaction proceeds readily in the liquid phase. The incorporation of an inert organic solvent is also useful, facilitating processing as well as agitation of the reactants. Temperatures that permit operation in the liquid phase and which are between room temperature and reflux temperature of the solvent, if any is used, are employed. Preferably the reaction mixture is refluxed, usually at an elevated temperature.

The dialkyl carbamic acid derivatives were prepared by the known reaction of an alcohol; e.g., a halo phenyl oxyalkanol with an N,N-dialkyl carbamyl chloride. In some instances it was found to be advantageous to use a catalyst, such as cupric chloride, to increase the reaction rate. The reaction involved the use of a slight excess of carbamyl chloride, heated usually between 50 C. to 100 C. with the desired aryloxy alcohol.

It has been found that the compounds of the present invention are particularly effective as herbicides. They are effective in the control of grasses and broadleaf plants with both preemergence and post-emergence activity.

The compounds of the present invention may be made in accordance with the following examples.

EXAMPLE 1 2,4-Dichlorophenoxyethyl-n-methyl carbamate. This example is representative of the preparation of mono-alkyl carbamic acid derivatives within the embodiment of the present invention. In 75 ml. of chloroform was dissolved 20.7 g. (0.1 M) of 2,4-dichlorophenoxyethanol with warming. Two drops of triethylamine were added as a catalyst thereby followed with the rapid addition of 6.8 g. (0.12 M) of methylisocyanate. The reaction mixture was then refluxed for three hours on a steam bath. The solvent and excess methylisocyanate were removed on a steam bath with an air jet. The solid product, 2,4-

EXAMPLE 2 2,4,S-Trichlorophenoxyethyl-N,N-di-n-propyl carbamate.

This example is representative of the preparation of N,N-dialkyl carbamic acid derivatives of the present invention. in l 1.4

Y g. (0.07 M) of N,N-di-n-propyl-carbamoyl chloride were dis-' solved by warming 12.1 g. (0.05 M) of 2,4,5-trichlorophenoxyethanol. To the reaction mixture was added 0.1 g. of cupric chloride dihydrate and hydrogen chloride evolution began at once. The mixture was heated on the steam bath under an air condenser for two hours. Excess carbamoyl chloride was removed with an air purge. The product was taken up in benzene, washed with dilute hydrochloric acid followed by a water wash. After drying over anhydrous magnesium sulfate the product was filtered and the solvent removed on a steam bath with an air jet. The liquid product weighed 18.] g. (98 percent of theory), n =l.52l8. Analysis; calculated for C H CI NO Chlorine, 28.9 percent, nitro ge n,3. 8 percent.

Eoundf Chlorine, 28.7 percent, nitrogen, 3 .9 percent.

The following is a table of the compounds prepared according to the aforedescribed procedures. Compound numbers have been assigned to each compound and are used throughout the balance of the application.

TABLE l R O ll N --OCH:CH:OR1

L.W my.

Compound Number R R R 1' methyl H 2,4-dichl0rophenyl 2 ethyl H 2,4-dichlorophenyl 3 n-butyl H 2,4-dichlorophenyl 4 ethyl H 2,4,5'trichlorophenyl 5 n-butyl H 2,4,5-trichlorophenyl 6 ethyl H pentachlorophenyl 7 ethyl ethyl 2,4,5-trichlorophenyl 8 methyl methyl 2,4,5-trichlorophenyl 9 n-propyl n-propyl 2,4,5-trichlcrophenyl l0 ethyl ethyl 2,4-dichlorophenyl l 1 methyl methyl 2,4-dichlorophenyl l2 n-propyl n-propyl 2,4-dichlorophenyl l3 allyl allyl 2,4-dichlorophenyl l4 allyl allyl 2,4,5-trichlorophenyl l5 ethyl n-butyl 2,4-dichlorophenyl l6 ethyl n-butyl 2,4,5-trichlorophenyl 17 methyl H 2,4,5-trichlorophenyl No. 1 prepared in Example 1 No. 9 prepared in Example 2.

As previously mentioned, the herein described novel compositions produced in the above described manner are phytotoxic compounds which are useful and valuable in controlling various plant species. The compounds of this invention were tested as herbicides in the following manner.

Pre-emergence Herbicide Test. The seeds of crab grass, foxtail, water grass, Pigweed, lndian mustard and dock were planted in individual rows one-half inch deep in Santa Cruz sandyloam soil contained in compressed paper flats 8-3 4 in. x 6-% in. which are 2% in. deep. Enough seeds were planted to give about 30 to 50 plants each of the weed species in each flat. The flats were watered after planting. The following day each flat was sprayed at the rate of 20 pounds of the candidate compound under test in 80 gallons of solution per acre. An

,atomizerwas used to-spray the solution on the soil surface. .Twolweeks later the degree of weed control was'determined by comparing the amount of germination and growth of each weedin the treated flats with weeds in several untreated con- 5 trol flats. The results oi this test are reported in Table ll.

TABLE II I Pro-emergence activity, rate lbs/A.

Corn and Crab Water-'1 Indian 7 Nurnmr grass 4 Foxtail grass Pigwaed mustard Dook +a-Blightl ury. -Modern injury Post-emergence Herbicides Test. The seeds of crab grass, water grass, Indian mustard, dock and pinto bean were planted in individual rows as described in the pro-emergence test,'supra. Two weeks after treatment the plant foliage-were sprayed with a rate equivalent to 12.5 pounds per acre. Two weeks after treatment the injury results wererecorded using a similar rating system as used in the preemergence text. Table Ill lists the results obtained therefrom.

TABLE nr Post-emergence activity, rate 12.6 lbs/A.

Compgund Crab Water Indiaii Pinto grass grass Mustard Dock an +=Siight in] '=lviorlerate iiijury. fff so ere injury or death.

The compounds of the present invention may be used as presemergence or post-emergence herbicides and may be applied in a variety of ways at various concentrations. in practice the compounds are formulated with an inert carrier, utilizing methods well known to those skilled in the art, thereby making them suitable for application as dusts, sprays, or drenches. The amount applied will depend on the nature of the seeds or plants to be controlled and the rate of application may vary I from 1 to 50 pounds per -acre. One particularly advantageous way of applying the compounds is as a narrow band along a row crop, straddling the row. 1

Various changes and, modifications may be made without departing from the spirit and scope of the invention described herein as will be apparent to those skilled in the art to which it pertains. it is accordingly intended that the present invention shall only be limited by the scope of the appended claims.

What is claimed is:

1. Method of combating weeds comprising applying thereto a phytotoxic amount of a compound wherein R and R are selected from the group consisting of hydrogen, lower alkyl having from one to six carbon atoms, inclusive, and lower alkenyl having from two to six carbon atoms, inclusive, at least one of R and R is a group other than hydrogen, and R is a. nuclearly substituted phenyl group wherein said substituents, are from one to five chlorine atoms, inclusive. 1 I '2. A method of combating weeds according to claim '1 wherein R is hydrogen, R is methyl, and R is 2,4 dichlorophenyl.

3. A method of combating weeds according to claim 1 wherein R is hydrogen, R is n-butyl, and R is 2,4- dichlorophenyl. V I Y 4. A method of combating weeds according to claim 1 wherein R is allyl, R is allyl, and R is 2,4,5-trichlorophenyl 5. A method of combating weeds according to claim' 1 wherein R is n-butyl, R is ethyl, and R is 2,4-dichlorophenyl.

6. A method of'combating weeds according to claim!- wherein R is hydrogen and R is lower alkyl having one to six carbon atoms, inclusive. g

7. A method of combating weeds according to claim 1 wherein R is lower alkyl having one to six carbon atoms, inclusive, and R is'lower alkyl having one to six carbon atoms, inclusive. i

sakes H059 UNlTED STATE PATENT OFFICE CEATiFlC TL OF COJMULC HUN Patent No. 3,652,258 Dated March 28, 1972 Inventor(s) Llewellyn W. Fancher 7 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

On Page 1, in the patent heading, the phrase ---assignor to Stauffer Chemical Company, New York, N.Y.-- should be inserted.

Column 1, line 6, the last word in the line, "of" should be deleted.

Column 3, line 370, the word "text" should read I Column 3, TABLE III for Compound No. 15 under the heading Indian Mustard, the entry reading "(-H-%-+ should read --(H-+ -z--'--. I

Signed and sealed this 3rd day of October 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTI'SCHALK Attesting Officer Commissioner of Patents 

2. A method of combating weeds according to claim 1 wherein R is hydrogen, R1 is methyl, and R2 is 2,4-dichlorophenyl.
 3. A method of combating weeds according to claim 1 wherein R is hydrogen, R1 is n-butyl, and R2 is 2,4-dichlorophenyl.
 4. A method of combating weeds according to claim 1 wherein R is allyl, R1 is allyl, and R2 is 2,4,5-trichlorophenyl.
 5. A method of combating weeds according to claim 1 wherein R is n-butyl, R1 is ethyl, and R2 is 2,4-dichlorophenyl.
 6. A method of combating weeds according to claim 1 wherein R is hydrogen and R1 is lower alkyl having one to six carbon atoms, inclusive.
 7. A method of combating weeds according to claim 1 wherein R is lower alkyl having one to six carbon atoms, inclusive, and R1 is lower alkyl having one to six carbon atoms, inclusive. 